td-io is a JVS I/O board designed to adapt older JAMMA-compatible cabinets to the newer JVS standard, used by modern arcade hardware such as the Naomi and exA. It features a number of independent systems to translate signals, drive cabinet hardware, and power JVS games.

JVS inputs

The JVS I/O bus connects to the board via USB-style A and B connectors. Daisy chaining is supported. The I/O presents two players, each with a single joystick/lever and six buttons. Joystick and button 1-4 inputs are mapped to the JAMMA edge connector, and buttons 4-6 are mapped to a CPS2-style kick harness connector. Buttons are polled on request, ensuring microsecond-level latency.

Service, test, and tilt buttons are also supported. JAMMA's single service button is mapped to JVS player 1's service button.

The board also presents one or two coin slots, toggleable by a DIP switch. The board also features two coin meter drivers and two coin lockout drivers. Coins are locked out when the respective coin count is set to its max value (16383).

Video

The board amplifies JVS-level video (0.7Vp-p) to JAMMA appropriate levels, by applying a gain of 3. Amplification is DC coupled, so sources that swing negative will also swing negative on the output. Max input and output swing is -3.5 to 3.5V.

In addition, a sync combiner combines negative H/V sync to negative composite sync.

An EDID EEPROM is also attached to the VGA port, to identify as a 31kHz monitor.

Audio

A class-D audio amplifier provides high power speaker drive to the JAMMA edge. In addition, an Egret 2-style stereo connector provides amplified stereo speaker driving. A swich selects between stereo and mono mixdown. There is also an analog pot for volume control.

Power

An 8-pin JVS power connector forwards 12V and 5V from the cabinet to the JVS board. In addition, an on-board power supply generates 3.3V at up to 8A from the cabinet's 5V rail for systems that require it, such as Naomi.

The IO's electronics are protected from overvoltage and overcurrent by an automatically resetting protector.

Firmware Updates

The board features an on-board RP2040 microcontroller, whose firmware can be updated over USB for feature enhancements or compatibility fixes.

Analog Input

The board features an unpopulated header exposing 3 3.3V level analog inputs, designed for potentiometers for analog joystick or racing games.

Where to buy

The board is not currently for sale, as testing is not yet complete.

License

CERN-OHL-W